Sheet-like sealing material, and laminate

Abstract

To provide a sheet-like seal material having a high adhesion strength with a variety of members notwithstanding curable in a short time at a low temperature.SOLUTION: A sheet-like seal material includes an epoxy compound, and a curing agent, and is uncured at a temperature of 25°C or lower. In the sheet-like seat material, a peel strength to an alkali-free glass after laminating with the alkali-free glass and heating at 100°C for 60 min. is 0.9 times or more and 1.1 times or less the peel strength to the alkali-free glass after laminating with the alkali-free glass and heating at 100°C for 30 min., and the storage elastic modulus E' at 35°C of a cured product obtained by dynamic viscoelasticity measurement at a rate of temperature rise of 5°C / min. and a frequency of 1 Hz is 0.1 GPa or more and 2.5 GPa or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a sheet-like sealing material and a laminate. [Background technology]

[0002] In recent years, thin display devices have become widespread. In such thin display devices, a display element such as an organic light-emitting diode (OLED) element is generally stacked with a back plate, a metal plate, or the like for supporting the display element. Furthermore, it is common to arrange an adhesive layer or an optical adhesive layer between each component, and to bond multiple components together. For example, Patent Document 1 discloses a configuration in which a substrate and an organic EL element are bonded together with an adhesive layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-141963 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a configuration in which components are bonded together using an adhesive sheet as in Patent Document 1, the adhesive sheet tends to wrinkle when subjected to thermal processing such as heat pressing, which can easily affect the display element.Furthermore, since the adhesive sheet does not harden, there is also the problem that it is difficult to fix it in the desired shape.

[0005] Here, it is conceivable to use a thermosetting sheet-like sealing material to bond the various components together. Such a sheet-like sealing material allows for fixing in a desired shape. The sheet-like sealing material needs to be cured by heating, but from the viewpoints of productivity and protection of the display element, it is desirable for it to be cured at a low temperature and in a short time. However, conventional sheet-like sealing materials tend to be poorly cured when heated at a low temperature and for a short time. Even if they can be cured, the adhesive strength between the cured product and various components is low, and especially when they are bonded to components with uneven surfaces, the adhesive strength decreases over time, and peeling can occur.

[0006] Therefore, an object of the present invention is to provide a sheet-like sealing material that can be cured at low temperature in a short time and yet has high adhesive strength to various members. [Means for solving the problem]

[0007] The present invention provides the following sheet-like sealing material and laminate. [1] A sheet-like sealing material comprising an epoxy compound and a curing agent, which remains uncured at 25°C or below, wherein the sheet-like sealing material is laminated with alkali-free glass and heated at 100°C for 60 minutes, and the peel strength from the alkali-free glass is 0.9 to 1.1 times the peel strength from the alkali-free glass after laminating the sheet-like sealing material with the alkali-free glass and heating at 100°C for 30 minutes; and the storage modulus E' at 35°C, as measured by dynamic viscoelasticity measurement at a heating rate of 5°C / min and a frequency of 1 Hz, is 0.1 GPa to 2.0 GPa. [2] The sheet-like sealing material according to [1], wherein the curing agent is a microcapsule-type curing agent and / or an acid generator having a sulfonium salt structure, in which at least one curing component selected from the group consisting of imidazole compounds, amine compounds, and amine adducts is encapsulated in microcapsules. [3] The sheet-like sealing material according to [1] or [2], further containing a dye. [4] A laminate comprising a first member, a second member, and an adhesive layer that bonds the first member and the second member, wherein at least one of the first member and the second member has irregularities with a height of 1 μm to 100 μm on a surface adjacent to the adhesive layer, and the adhesive layer is a cured product of the sheet-like sealing material described in any one of [1] to [3]. [5] The laminate according to [4], wherein the height of the irregularities is 80% or less of the thickness of the adhesive layer. [Effects of the Invention]

[0008] The sheet-like sealing material of the present invention can be cured at low temperatures in a short time, and the cured product has very high adhesive strength to various members. DETAILED DESCRIPTION OF THE INVENTION

[0009] 1. Sheet-type sealing material The sheet-like sealing material of the present invention is useful as a sheet for bonding components of various display devices together. However, the use of the sheet-like sealing material of the present invention is not limited to display devices, and it can be used for various purposes.

[0010] As mentioned above, it has been difficult to sufficiently cure conventional sheet-like sealing materials at low temperatures in a short time. Even when cured, the adhesive strength between the cured product (adhesive layer) and various components is low, making peeling and other problems likely to occur over time. For example, one possible reason for this is that the use of highly reactive polyfunctional components or low-molecular-weight components to enhance curing properties tends to result in hard, brittle cured products. In contrast, the sheet-like sealing material of the present invention, after being laminated with alkali-free glass and heated at 100°C for 60 minutes, exhibits a peel strength from the alkali-free glass that is 0.9 to 1.1 times the peel strength from the alkali-free glass after being laminated with alkali-free glass and heated at 100°C for 30 minutes. In other words, the sheet-like sealing material stabilizes its cured state and is substantially cured after 30 minutes of heating at 100°C. On the other hand, by including the epoxy resin and curing agent described below, the cured product of the sheet-like sealing material has a storage modulus E' at 35°C, as determined by dynamic viscoelasticity measurement, of 0.1 GPa or more and 2.0 GPa or less. Through extensive research by the present inventors, it has become clear that a cured product having such a storage modulus E' can exhibit high adhesive strength, even to components having uneven surfaces. The reasons for this are thought to be as follows: If the storage modulus E' of the cured product is too low, the cured product is too soft and easily undergoes plastic deformation when an external force is applied, making it impossible to maintain sufficient adhesive strength. On the other hand, if the storage modulus E' of the cured product is too high, the cured product cannot follow the deformation of various components when an external force is applied, and peeling is likely to occur at the interface between them. In contrast, when the storage modulus E' of the cured product is within the above range, the cured product is less likely to undergo plastic deformation and can deform in response to the deformation of various components. Furthermore, even when bonded to an uneven component, peeling is less likely to occur at the interface between them, and the adhesion strength is less likely to decrease.

[0011] The peel strength of the sheet-like sealing material against alkali-free glass after 30 minutes of heating and after 60 minutes of heating is measured as follows: A sheet-like sealing material measuring 25 mm in width and 100 mm in length is prepared, and one side of the sheet-like sealing material is adhered to a 50 mm in width and 70 mm in length of alkali-free glass and thermocompressed at 70°C. The other side of the sheet-like sealing material is adhered to an aluminum-vapor-deposited PET film measuring 25 mm in width and 100 mm in length and thermocompressed at 70°C to obtain a test piece. Two test pieces are prepared, one of which is heated at 100°C for 30 minutes and the other at 100°C for 60 minutes. The alkali-free glass is then fixed to a universal testing machine, and the aluminum-vapor-deposited PET film and the sheet-like sealing material are pulled vertically at a peel rate of 30 mm / min to measure the strength required for peeling.

[0012] Here, the sheet-like sealing material of the present invention can be cured in a short time by heating at 100°C as described above, but remains uncured at temperatures below 25°C. In this specification, "uncured at temperatures below 25°C" means that the calorific value measured by a differential scanning calorimeter (DSC) for the sheet-like sealing material after storage at 25°C for one day after production is 0.95 to 1.05 times the calorific value measured by the differential scanning calorimeter (DSC) for the sheet-like sealing material immediately after production. Specifically, 10 mg of each sheet-like sealing material is sampled and placed in an aluminum cell for DSC measurement to prepare a measurement test sample. Then, the calorific values of these measurement test samples are determined and compared when their temperature characteristics are measured at a heating rate of 5°C / min over a temperature range of 20°C to 300°C. A small difference in the calorific values indicates that the curing reaction of the epoxy compound does not progress during storage at 25°C for one day, and the sheet-like sealing material is stable.

[0013] The sheet-like sealing material of the present invention may contain at least an epoxy compound and a curing agent, but may further contain an oxetane compound, a tackifier, a dye, and other components as necessary. Each component and the physical properties of the sheet-like sealing material and its cured product will be described below.

[0014] (epoxy compounds) In this specification, an epoxy compound refers to a compound having one or more epoxy groups per molecule. The epoxy compound is not particularly limited as long as it can be cured with a curing agent described below and has a storage modulus E' within the above range after curing. Here, the sheet-like sealing material preferably contains two or more epoxy compounds, and more preferably contains (i) an epoxy compound having a cycloalkene oxide structure, (ii) a high-molecular-weight epoxy compound having a weight-average molecular weight of 3000 or more, and (iii) a flexibility-imparting epoxy compound having a weight-average molecular weight of 300 or more but less than 3000. By including such multiple types of epoxy compounds, the storage modulus E' of the cured product is more likely to fall within the above range.

[0015] (i) In an epoxy compound having a cycloalkene oxide structure, the "cycloalkene oxide structure" is a structure represented by the following general formula, which is obtained by epoxidizing a cycloalkene with an oxidizing agent such as a peroxide, and has an aliphatic ring and an epoxy group composed of two carbon atoms and an oxygen atom constituting the aliphatic ring. [ka] In the above general formula, M represents an alicyclic structure, and the number of carbon atoms therein is preferably 4 to 8, more preferably 5 to 6. (i) When the number of carbon atoms in the alicyclic structure of the cycloalkene oxide structure is within this range, the physical properties of the sheet-shaped sealing material tend to fall within the desired ranges.

[0016] Specific examples of the cycloalkene oxide structure include cyclohexene oxide and cyclopentene oxide, with cyclohexene oxide being preferred.

[0017] (i) The number of cycloalkene oxide structures contained in one molecule of an epoxy compound having a cycloalkene oxide structure may be one (monofunctional) or two or more (multifunctional), and among these, the number of cycloalkene oxide structures in one molecule is preferably two or more (multifunctional).

[0018] (i) Examples of epoxy compounds having a cycloalkene oxide structure include compounds represented by the following general formulas (i-1) to (i-3).

[0019] [ka]

[0020] M in the above general formula (i-1) 1 and M 2 represents an alicyclic structure, and as described above, the number of carbon atoms therein is preferably 4 to 8, more preferably 5 to 6. X in the above general formula (i-1) 1 is a single bond or a linking group. Examples of the linking group include a divalent hydrocarbon group, a carbonyl group, an ether group (ether bond), a thioether group (thioether bond), an ester group (ester bond), a carbonate group (carbonate bond), an amide group (amide bond), or a group in which multiple of these are linked together.

[0021] Examples of divalent hydrocarbon groups that can be the linking group include alkylene groups having 1 to 18 carbon atoms and divalent alicyclic hydrocarbon groups. Examples of alkylene groups having 1 to 18 carbon atoms include methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene. Examples of divalent alicyclic hydrocarbon groups include divalent cycloalkylene groups (including cycloalkylidene groups) such as 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylidene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, and cyclohexylidene.

[0022] Among them, X 1is preferably a single bond or a linking group having an oxygen atom. The linking group having an oxygen atom is more preferably -CO- (carbonyl group), -O-CO-O- (carbonate group), -COO- (ester group), -O- (ether group), -CONH- (amide group), a group in which a plurality of these groups are linked together, or a group in which one or more of these groups are linked to one or more divalent hydrocarbon groups.

[0023] Specific examples of the alicyclic epoxy compound represented by the general formula (i-1) above include the following compounds. In the following formula, l is an integer of 1 to 10, and m is an integer of 1 to 30. R is an alkylene group having 1 to 8 carbon atoms (preferably an alkylene group having 1 to 3 carbon atoms, such as a methylene group, an ethylene group, a propylene group, or an isopropylene group). n1 and n2 are each an integer of 1 to 30.

[0024] [ka]

[0025] Examples of commercially available epoxy compounds represented by the general formula (i-1) include Celloxide 2021P, Celloxide 2081, Celloxide 8000, and Celloxide 8010 (manufactured by Daicel Corporation).

[0026] On the other hand, (i) the epoxy compound having a cycloalkene oxide structure may be, for example, a compound having a structure represented by the following general formula (i-2) or (i-3). [ka] M in the above general formulae (i-2) and (i-3) 3 , M 4 , and M 5 represents an alicyclic structure, and the number of carbon atoms therein is preferably 4 to 8, and more preferably 5 to 6. X in the above general formula (i-3) 2is a single bond or a linking group. The linking group is the same as the linking group in the above-mentioned general formula (i-1). In addition, the compounds represented by general formulas (i-2) and (i-3) may have an alkyl group or the like bonded to a carbon that constitutes an alicyclic structure or an epoxy group.

[0027] Examples of epoxy compounds represented by the general formula (i-2) or (i-3) include 3,4:7,8-diepoxybicyclo[4.3.0]nonane and limonene dioxide, etc. Commercially available examples of these compounds include THI-DE (manufactured by JX-TG Corporation) and LDO (manufactured by Nagase Chemtec Corporation).

[0028] The weight-average molecular weight of any of the above-mentioned (i) epoxy compounds having a cycloalkene oxide is preferably 180 or more, more preferably 190 or more, and even more preferably 200 or more. The upper limit of the weight-average molecular weight is appropriately selected depending on the desired performance of the sheet-like sealing material, but is preferably 500 or less. When the weight-average molecular weight of the (i) epoxy compound having a cycloalkene oxide is 180 or more, the physical properties of the sheet-like sealing material tend to fall within the desired range. The weight-average molecular weight of the epoxy compound is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0029] In particular, (i) the epoxy compound having a cycloalkene oxide is preferably a compound represented by the following formula, from the viewpoint that the storage modulus E' of the cured product is more likely to fall within the desired range. [ka]

[0030] When the sheet-shaped sealing material contains (i) an epoxy compound having a cycloalkene oxide, the total amount thereof is preferably 5% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 30% by mass or less, based on the total amount of the sheet-shaped sealing material. When the amount of the epoxy compound is within this range, the physical properties of the cured product of the sheet-shaped sealing material are more likely to fall within the desired range.

[0031] (ii) A high-molecular-weight epoxy compound having a weight-average molecular weight of 3,000 or more is solid at room temperature (25°C). The weight-average molecular weight of the (ii) high-molecular-weight epoxy compound is preferably 3,000 or more and 100,000 or less, more preferably 6,000 or more and 60,000 or less, and even more preferably 7,000 or more and 40,000 or less. When a sheet-shaped sealing material contains the (ii) high-molecular-weight epoxy compound, the sheet-shaped sealing material is more likely to maintain its shape. Furthermore, when the (ii) high-molecular-weight epoxy compound has a weight-average molecular weight of 100,000 or less, the sheet-shaped sealing material exhibits good fluidity when heated and bonded, making it easier to adhere to various components. The weight-average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0032] (ii) The high molecular weight epoxy compound may be an aromatic epoxy compound or an aliphatic epoxy compound, but a compound having an aromatic ring is more preferred.

[0033] Specific examples of aromatic epoxy compounds that can be the (ii) high-molecular-weight epoxy compounds include bisphenol-type epoxy resins such as bisphenol A, bisphenol F, bisphenol E, bisphenol S, bisphenol AD, and mixtures thereof; diphenyl ether-type epoxy resins; novolac-type epoxy resins such as phenol novolac, cresol novolac, biphenyl novolac, bisphenol novolac, naphthol novolac, trisphenol novolac, and dicyclopentadiene novolac; biphenyl-type epoxy resins; naphthyl-type epoxy resins; and triphenolalkane-type epoxy resins such as triphenolmethane, triphenolethane, and triphenolpropane.

[0034] Among the above aromatic epoxy compounds, bisphenol-type epoxy resins or biphenyl-type epoxy resins are preferred. However, as the amount of bisphenol F skeleton in the sheet-shaped sealing material increases, the softening point of the sheet-shaped sealing material tends to decrease. Therefore, when the sheet-shaped sealing material is bonded to various members at a relatively high temperature, it is preferred that the sheet-shaped sealing material mainly contains an aromatic epoxy compound other than a bisphenol F skeleton.

[0035] Furthermore, while the number of epoxy groups possessed by the (ii) high-molecular-weight epoxy compound is not particularly limited, the epoxy equivalent is preferably 900 g / eq or more and 20,000 g / eq or less, and more preferably 1,000 g / eq or more and 20,000 g / eq or less. When the epoxy equivalent of the (ii) high-molecular-weight epoxy compound is 900 g / eq or more, the tackiness of the sheet-shaped sealing material at room temperature is reduced. Therefore, the handling properties of the sheet-shaped sealing material tend to be improved. On the other hand, if the epoxy equivalent of the (ii) high-molecular-weight epoxy compound is excessively large, the solubility of the (ii) high-molecular-weight epoxy compound in solvents may decrease or its compatibility with other epoxy compounds may become poor. Therefore, the epoxy equivalent of the (ii) high-molecular-weight epoxy compound is preferably 20,000 g / eq or less.

[0036] The total amount of (ii) high molecular weight epoxy compound relative to the total amount of the sheet-like sealing material is preferably 1% by mass to 50% by mass, more preferably 5% by mass to 40% by mass, and even more preferably 10% by mass to 35% by mass. When the amount of (ii) high molecular weight epoxy compound in the sheet-like sealing material is within this range, the lamination temperature between the sheet-like sealing material and various components tends to be appropriate.

[0037] Furthermore, the (iii) flexibility-imparting epoxy compound may be an epoxy compound having a weight-average molecular weight of 300 or more but less than 3,000, and more preferably a weight-average molecular weight of 500 or more but less than 2,000. The (iii) flexibility-imparting epoxy compound may be a solid or liquid at room temperature (25°C). The (iii) flexibility-imparting epoxy compound may be an aromatic epoxy compound or an aliphatic epoxy compound.

[0038] Specific examples of (iii) the flexibility-imparting epoxy compound when it is an aromatic epoxy compound include the aromatic epoxy compounds listed above in (ii) the high-molecular-weight epoxy compounds and similar resins (however, the molecular weight is 300 or more and less than 3,000).

[0039] On the other hand, when the (iii) flexibility-imparting epoxy compound is an aliphatic epoxy compound, the aliphatic epoxy compound may be a compound having one or more epoxy groups in the molecule and an aliphatic chain (excluding those corresponding to the epoxy compounds (i) or (ii) above). The aliphatic epoxy compound may have only one epoxy group, or may have two or more epoxy groups. Furthermore, the length of the aliphatic chain contained in the aliphatic epoxy compound is not particularly limited, but the number of carbon atoms in the molecule is preferably 10 to 1,000, and more preferably 50 to 200. If the number of carbon atoms in the molecule is 10 or more, the storage modulus E' of the cured product of the sheet-like sealing material tends to be low. On the other hand, if the number of carbon atoms in the molecule is 1,000 or less, the compound is more likely to be compatible with other components.

[0040] The total amount of the (iii) flexibility-imparting epoxy compound relative to the total amount of the sheet-like sealing material is preferably 15% by mass to 45% by mass, more preferably 20% by mass to 40% by mass, and even more preferably 25% by mass to 35% by mass. When the amount of the (iii) flexibility-imparting epoxy compound in the sheet-like sealing material is within this range, the storage modulus E' of the cured product of the sheet-like sealing material is more likely to fall within the desired range.

[0041] The sheet-shaped sealing material may further contain an epoxy compound other than the above-mentioned (i) epoxy compound having a cycloalkene oxide structure, (ii) high-molecular-weight epoxy compound, and (iii) flexibility-imparting epoxy compound.

[0042] The total amount of the epoxy compound relative to the total amount of the sheet-like sealing material is preferably 50% by mass or more and 95% by mass or less, more preferably 60% by mass or more and 90% by mass or less, and even more preferably 65% by mass or more and 85% by mass or less. When the amount of the epoxy compound in the sheet-like sealing material is within this range, the strength of the sheet-like sealing material and its cured product can be sufficiently increased. In addition, the thermosetting properties of the sheet-like sealing material tend to be good.

[0043] (hardening agent) The type of curing agent contained in the sheet-shaped sealing material of the present invention is not particularly limited, as long as it is a component that does not cure the sheet-shaped sealing material at temperatures below 25°C, but can cure the sheet-shaped sealing material by heating at 100°C for a short period of time (e.g., about 30 minutes), as described above.

[0044] An example of the curing agent is a microcapsule-type curing agent in which various curing components are encapsulated in microcapsules. The sheet-shaped sealing material may contain only one type of microcapsule-type curing agent, or may contain two or more types.

[0045] Examples of the curing component encapsulated in the microcapsules include imidazole compounds, amine compounds, amine adducts, etc. The curing agent may contain only one type of curing component, or may contain two or more types.

[0046] Examples of imidazole compounds include imidazole, 1-methylimidazole, 2-methylimidazole, 1,2-dimethylimidazole, 4-methylimidazole, 2-ethyl-4-methylimidazole, 2-ethylimidazole, 2-butylimidazole, 1-vinylimidazole, 2-methyl-1-vinylimidazole, 1-allylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 4-formylimidazole, 2-butyl-4-formylimidazole, dazole, 2-butyl-4-hydroxymethylimidazole, 2-butyl-4-chloro-5-formylimidazole, 2-hydroxymethylimidazole, 1-(2-hydroxyethyl)-imidazole, 1-(2-hydroxyethyl)-2-methylimidazole, 2-hydroxymethyl-1-benzylimidazole, 4-hydroxymethyl-2-methylimidazole, 4-formyl-1-methylimidazole, 5-formyl-1-methylimidazole, 4-formyl-5-methylimidazole, 4-formyl-1-tritylimidazole, 4-Carboxymethylimidazole, 4-carboxyethylimidazole, 4-carboxylic acid imidazole, 2-aminoimidazole sulfate, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-formylimidazole, 1-benzyl-5-hydroxymethylimidazole, 1-benzyl-5-hydroxymethylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethylimidazole, 4-methylimidazole, 1 -cyanoethyl-2-phenylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-aminoethyl-2-methylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-methylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-ethyl-4-methylimidazole, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazole, and the like.

[0047] Examples of the amine compound include methylamine, ethylamine, propylamine, butylamine, ethylenediamine, 1,2-propanediamine, tetramethyleneamine, 1,5-diaminopentane, hexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 2,2,4-triethylhexamethyldiamine, 1,2-diaminopropane, diethylenetriamine, triethylenetetramine, tetraethylenepentane, cyclohexylamine, isophoronediamine, 1,3-bisaminomethylcyclohexane, aminoethylpiperazine, diethylaminopropylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, dimethanolamine, diethanolamine, dipropanolamine, dicyclohexylamine, piperazine, and the like.

[0048] An amine adduct is an addition compound obtained by reacting a compound having an amine structure with any compound. Examples of the amine adduct include addition compounds obtained by reacting the above-mentioned imidazole compounds or amine compounds with carboxylic acid compounds, sulfonic acid compounds, epoxy resins, etc. (for example, epoxy resins obtained by glycidylating bisphenol F, resins obtained by glycidylating bisphenol A, etc.).

[0049] On the other hand, the capsules encapsulating the curing component are not particularly limited in structure or material as long as they rupture or expand when heated and the curing component can come into contact with the above-mentioned epoxy compound, but it is preferable that the capsules be epoxy resins, as this makes it easier to exhibit the above-mentioned performance.

[0050] Here, the average particle size of the microcapsule-type curing agent is not particularly limited, but is preferably, for example, more than 0.3 μm and not more than 13 μm, and more preferably 1 μm or more and not more than 11 μm. Furthermore, the curing component encapsulated in the capsules is preferably solid, and its average particle size is preferably more than 0.25 μm and not more than 12 μm, and more preferably more than 1 μm and not more than 10 μm. When the average particle size of the curing component or the average particle size of the microcapsule-type curing agent encapsulating the curing component is within the above range, the curing component is more likely to perform its function uniformly in the sheet-like sealing material when heated. The above average particle size is the Stokes diameter measured by laser diffraction / light scattering.

[0051] The microcapsule-type curing agent can be produced by a known method. For example, a curing component having a desired average particle size may be prepared, dispersed in a dispersion medium together with capsule components, and the capsule components may be precipitated on the surface of the curing component. Alternatively, a solution may be prepared by dissolving capsule raw materials in a solvent, and the curing component may be added to the solution, and the capsule raw materials may be reacted on the surface of the curing component to form capsules.

[0052] The microcapsule-type curing agent, in which the curing component is encapsulated in microcapsules, may be a commercially available product. Examples of commercially available products include Novacure (registered trademark) HX-3742, HX-3722, HXA-3922HP, HXA-4922HP, and HXA-4922HP (all manufactured by Asahi Kasei Corporation). Note that the commercially available products are distributed in a state in which the microcapsule-type curing agent is dispersed in an epoxy compound (e.g., bisphenol A epoxy resin).

[0053] When the curing agent is the microcapsule-type curing agent, the amount of the curing component in the sheet-like sealing material is preferably 1% by mass or more and 15% by mass or less, and more preferably 3% by mass or more and 10% by mass or less, relative to the total amount of the sheet-like sealing material. When the amount of the curing component of the microcapsule-type curing agent in the sheet-like sealing material is within this range, the curability of the sheet-like sealing material can be further improved, and the sheet-like sealing material can be cured by heating at a low temperature for a short time.

[0054] On the other hand, the curing agent may be a thermal acid generator having a sulfonium salt structure that generates an acid upon heating. Examples of such thermal acid generators having a sulfonium salt structure include CF3SO3 - and a thermal acid generator containing a quaternary ammonium salt.

[0055] When the curing agent is a thermal acid generator having the sulfonium salt structure, the amount of the thermal acid generator in the sheet-like sealing material is preferably 1% by mass to 15% by mass, more preferably 3% by mass to 10% by mass, based on the total amount of the sheet-like sealing material. When the amount of the thermal acid generator is within this range, the curability of the sheet-like sealing material can be further improved, and the sheet-like sealing material can be cured by heating at 100°C for a short period of time (for example, about 30 minutes).

[0056] (tackifier) The sheet-shaped sealing material may further contain a tackifier, which is a component for imparting adhesiveness to the sheet-shaped sealing material.

[0057] The type of tackifier is not particularly limited as long as it is a component that is easily miscible with the epoxy compound, but the tackifier is preferably a resin selected from the group consisting of petroleum resins (aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, and / or aromatic hydrocarbon resins), terpene resins, phenolic resins, and rosin resins. The sheet-like sealing material may contain only one type of tackifier, or may contain two or more types.

[0058] Examples of petroleum resins include C5 monomers or oligomers thereof obtained from pentene, pentadiene, isoprene, etc.; C9 monomers or oligomers thereof obtained from indene, methylindene, vinyltoluene, styrene, α-methylstyrene, β-methylstyrene, etc.; copolymers of C5 and C9 monomers (C5-C9 copolymer resins); alicyclic monomers or polymers thereof obtained from cyclopentadiene, dicyclopentadiene, etc.; aromatic monomers such as isopropenyltoluene or polymers thereof; hydrogenated products of the above-mentioned various monomers or polymers thereof; and modified petroleum resins obtained by modifying the above-mentioned various monomers or polymers thereof with maleic anhydride, maleic acid, fumaric acid, (meth)acrylic acid, phenol, etc.

[0059] Examples of terpene resins include α-pinene resins, β-pinene resins, α-pinene monomers, and aromatic-modified terpene resins obtained by copolymerizing terpenes such as β-pinene monomers with aromatic monomers such as styrene and phenol.

[0060] Examples of phenolic resins include condensates of phenols and formaldehyde. Examples of phenols include phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcinol, etc. Examples of the phenolic resins include resols obtained by addition reaction of these phenols with formaldehyde using an alkali catalyst, and novolacs obtained by condensation reaction using an acid catalyst. Phenolic resins also include rosin phenolic resins obtained by adding phenol to rosin using an acid catalyst and thermally polymerizing the resulting mixture.

[0061] Examples of rosin resins include gum rosin, wood rosin, or tall oil rosin; stabilized rosins or polymerized rosins obtained by disproportionating or hydrogenating these rosins; modified rosins obtained by modifying these rosins with maleic anhydride, maleic acid, fumaric acid, (meth)acrylic acid, phenol, or the like; and esters thereof. The alcohol used to obtain the esters is preferably a polyhydric alcohol. Examples of polyhydric alcohols include dihydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, and neopentyl glycol; trihydric alcohols such as glycerin, trimethylolethane, and trimethylolpropane; tetrahydric alcohols such as pentaerythritol and diglycerin; and hexahydric alcohols such as dipentaerythritol. These may be used alone or in combination during esterification.

[0062] Among the above, a terpene-phenol tackifier, which is a combination of a terpene resin and a phenol resin, is preferred from the viewpoint of compatibility with epoxy compounds.

[0063] The amount of tackifier in the sheet-shaped sealing material is preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less, relative to the total amount of the sheet-shaped sealing material.When the amount of tackifier is within this range, the sheet-shaped sealing material tends to be easy to handle.

[0064] (Oxetanyl group-containing compounds) The sheet-shaped sealing material may further contain an oxetanyl group-containing compound. In this specification, "oxetanyl group-containing compound" refers to a compound having at least one oxetanyl group in the molecule and capable of being cured by the above-mentioned curing agent. The number of oxetanyl groups in the oxetanyl group-containing compound is preferably 1 to 5, but from the viewpoint of thermosetting properties, 2 or more is more preferable, and 2 is particularly preferable. The sheet-shaped sealing material may contain only one type of oxetanyl group-containing compound, or may contain two or more types.

[0065] Examples of oxetanyl group-containing compounds having only one oxetanyl group include 2-ethylhexyl oxetane, 3-ethyl-3-hydroxymethyl oxetane, 3-(meth)allyloxymethyl-3-ethyloxetane, (3-ethyl-3-oxetanylmethoxy)methylbenzene, 2-ethylhexyl (3-ethyl-3-oxetanylmethyl) ether, ethyl diethylene glycol (3-ethyl-3-oxetanylmethyl) ether, 3-cyclohexylmethyl-3-ethyloxetane, etc. Among these, 2-ethylhexyl oxetane (e.g., Aron Oxetane OXT-212, manufactured by Toagosei Chemical Co., Ltd.) is preferred from the viewpoint of availability, etc.

[0066] Examples of the oxetanyl group-containing compound having two oxetanyl groups include 1,4-bis{[(3-ethyl-3-oxetanyl)methoxy]methyl}benzene, 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, 1,4-bis[(3-ethyl-3-oxetanyl)methoxy]benzene, 1,3-bis[(3-ethyl-3-oxetanyl)methoxy]benzene, 3,7-bis(3-oxetanyl)- Examples of suitable esters include 5-oxa-nonane, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]ethane, 1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, ethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, and dicyclopentenyl bis(3-ethyl-3-oxetanylmethyl)ether. Among these, 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane (e.g., Aron Oxetane OXT-221, manufactured by Toagosei Chemical Co., Ltd.) is preferred from the viewpoint of availability.

[0067] Examples of the oxetanyl group-containing compound having three or more oxetanyl groups include trimethylolpropane tris(3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tris(3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tetrakis(3-ethyl-3-oxetanylmethyl) ether, and dipentaerythritol pentakis(3-ethyl-3-oxetanylmethyl) ether.

[0068] When the sheet-shaped sealing material contains an oxetanyl group-containing compound, the amount thereof is preferably 1% by mass to 50% by mass, more preferably 3% by mass to 30% by mass, based on the total amount of the sheet-shaped sealing material. When the amount of the oxetanyl group-containing compound is within this range, the sheet-shaped sealing material tends to have good curability.

[0069] (dye) The sheet-like sealing material of the present invention may contain a dye, if necessary. The dye may be added for the purpose of coloring the sheet-like sealing material, or may be added to adjust the storage modulus E' of the cured product of the sheet-like sealing material. When the sheet-like sealing material contains a dye, the storage modulus E' of the cured product of the sheet-like sealing material tends to be lower. The sheet-like sealing material may contain only one type of dye, or may contain two or more types of dyes.

[0070] The dye may be either a natural dye or a synthetic dye (e.g., monoazo dye, disazo dye, metal complex dye, acid dye, reactive dye, direct dye, disperse dye, cationic dye, etc.), but is preferably oil-soluble in terms of compatibility with other components of the sheet-like sealing material.

[0071] Examples of oil-soluble dyes include oil black, Varifast black (black), oil yellow, Varifast yellow, nickel titanium yellow (yellow), oil red, Varifast red, Congo red (red), and malachite green (blue-green).

[0072] When the sheet-shaped sealing material contains a dye, the amount thereof is preferably 1% by mass or more and 30% by mass or less, and more preferably 5% by mass or more and 20% by mass or less, relative to the total amount of the sheet-shaped sealing material. When the amount of the dye is within this range, not only is it easy to obtain the desired color, but also the storage modulus E' of the cured product is more likely to fall within the desired range.

[0073] (Other ingredients) The sheet-shaped sealing material may further contain components other than those described above, provided that the objectives and effects of the present invention are not impaired. For example, the sheet-shaped sealing material may contain, as other components, resins other than the above-mentioned epoxy compounds and oxetanyl group-containing compounds. Examples of other resins include polyamide, polyamideimide, polyurethane, polybutadiene, polychloroprene, polyether, polyester, styrene-butadiene-styrene block copolymers, xylene resins, ketone resins, cellulose resins, fluorine-based oligomers, silicon-based oligomers, polysulfide-based oligomers, etc. The sheet-shaped sealing material may contain only one of these, or two or more of them.

[0074] Furthermore, the sheet-shaped sealing material may further contain fillers, modifiers, stabilizers, etc., within the scope that does not impair the object and effect of the present invention.

[0075] Examples of the filler include glass beads, styrene-based polymer particles, methacrylate-based polymer particles, ethylene-based polymer particles, propylene-based polymer particles, etc. The sheet-shaped sealing material may contain only one type of filler, or may contain two or more types of filler.

[0076] Specific examples of the modifier include a polymerization initiator, an antioxidant, a leveling agent, a wettability improver, a surfactant, a plasticizer, a solvent, a silane coupling agent, etc. The sheet-like sealing material may contain only one of these modifiers, or may contain two or more of them.

[0077] Specific examples of stabilizers include ultraviolet absorbers, antiseptics, antibacterial agents, etc. The sheet-shaped sealing material may contain only one of these, or may contain two or more of them.

[0078] However, the amount of other components is preferably 10% by mass or less, and more preferably 5% by mass or less, based on the total amount of the sheet-shaped sealing material.

[0079] (Sheet-type sealing material and its cured properties) The sheet-like sealing material may be formed into a sheet by mixing the above-mentioned epoxy compound and curing agent, as well as a tackifier, an oxetanyl group-containing compound, a dye, and other components. The sheet-like sealing material may be distributed with a separator disposed on one or both sides, for example. Furthermore, the sheet-like sealing material may be distributed with desired components disposed on one or both sides, as described below in connection with the laminate.

[0080] The thickness of the sheet-like sealing material is appropriately selected depending on the application of the sheet-like sealing material. When the sheet-like sealing material is used to bond various components of a display device, the thickness of the sheet-like sealing material is preferably 3 μm or more and 100 μm or less, and more preferably 7 μm or more and 40 μm or less. When the thickness of the sheet-like sealing material is 3 μm or more, the layer made of the cured product of the sheet-like sealing material can easily absorb and relieve stress applied to various components, making it easier to suppress cracks and dents. Furthermore, even when various components have unevenness, the sheet-like sealing material can easily conform to the uneven shape and adhere to the components, making the adhesive strength good. On the other hand, when the thickness of the sheet-like sealing material is 100 μm or less, it becomes easier to reduce the thickness and weight of the display device.

[0081] Furthermore, the sheet-shaped sealing material is usually heated to a temperature below 100°C to soften (or melt) it before being attached to a desired member. Therefore, the softening (melting) temperature of the sheet-shaped sealing material is preferably 35°C or higher and 60°C or lower. However, it is preferable to adjust this temperature appropriately depending on the method of attaching the sheet-shaped sealing material to another member and the object to be attached.

[0082] Furthermore, when the sheet-shaped sealing material is bonded to various components, the sheet-shaped sealing material is softened (melted), making it less likely to produce gaps between the various components. If the melting temperature of the sheet-shaped sealing material is 60°C or lower, the sheet-shaped sealing material can be bonded to various components at a relatively low temperature (60°C or lower). On the other hand, if the melting temperature of the sheet-shaped sealing material is 35°C or higher, the tackiness of the sheet-shaped sealing material during operation (tackiness at room temperature) is reduced, making it easier to work with. Furthermore, the sheet-shaped sealing material is less likely to deform during storage, and can maintain its shape.

[0083] The melting temperature can be measured as follows. A strip-shaped test piece is prepared by cutting a sheet-shaped sealing material into a length of approximately 30 mm and a width of approximately 5 mm. This test piece is then attached to a glass plate heated on a hot plate. The test piece is then gradually peeled off from the glass plate in a 180° direction. This procedure is repeated, starting with a hot plate temperature of 40°C, and a new strip-shaped test piece is prepared every time the set temperature is increased by 1°C. The temperature at which the adhesive peelability of the layer made of the sheet-shaped sealing material is greatest upon peeling is taken as the melting temperature. However, if the adhesive peelability is already high at 40°C, the melting temperature is measured from 25°C.

[0084] On the other hand, the heat generation initiation temperature of the sheet-like sealing material measured by a differential scanning calorimeter (DSC) is preferably 60°C or higher and 90°C or lower, and more preferably 65°C or higher and 85°C or lower. If the heat generation initiation temperature is 60°C or higher, the epoxy compound is less likely to harden when the sheet-like sealing material is used to produce a laminate described below or when the produced laminate is stored, resulting in good storage stability. On the other hand, if the heat generation initiation temperature is 90°C or lower, the sheet-like sealing material can be cured at 90°C or lower, which makes it less likely to affect the object to be bonded. The heat generation initiation temperature can be measured by the following method. First, 10 mg of the sheet-like sealing material is sampled and placed in an aluminum cell for DSC measurement to prepare a measurement test sample. Then, the temperature characteristics of the measurement test sample are measured at a temperature rise rate of 5°C / min in a measurement temperature range of 20°C to 300°C, thereby identifying the heat generation initiation temperature.

[0085] Furthermore, as described above, the storage modulus E' at 25°C of the cured product of the sheet-like sealing material, i.e., the cured product after the adhesive strength between the sheet-like sealing material and the member has stabilized, i.e., after another 30 minutes of heating for curing, in which the peel strength of the sheet-like sealing material to alkali-free glass is within ±10% of the peel strength before 30 minutes of heating, may be 0.1 GPa to 2.5 GPa. Depending on the application, it may be 0.5 GPa to 2.0 GPa. Note that the storage modulus E' in this specification is a value measured by dynamic viscoelasticity measurement at a heating rate of 5°C / min and a frequency of 1 Hz.

[0086] 2.Laminate The sheet-like sealing material described above can be attached to various components such as display devices to form a laminate. One example of a laminate includes a first member, a second member, and an adhesive layer that bonds them together, and at least one of the first member and the second member has irregularities with a height of 1 μm to 100 μm on the surface adjacent to the adhesive layer. In this laminate, the adhesive layer is a cured product of the sheet-like sealing material described above. The height of the irregularities is preferably equal to or less than the thickness of the sheet-like sealing material; that is, the height of the irregularities is preferably 100% or less, more preferably 80% or less, of the thickness of the sheet-like sealing material.

[0087] As described above, the storage modulus E' of the cured product of the sheet-like sealing material (here, the adhesive layer) is within a predetermined range. Therefore, even if the first member and the second member have uneven surfaces, they can be firmly bonded together by the adhesive layer, and a highly reliable laminate can be obtained.

[0088] Here, the shapes of the first and second members can be selected appropriately depending on the application, and may be, for example, film-like or plate-like.

[0089] The materials of the first and second members are not particularly limited and may be metal, inorganic, or organic, including various metals such as SUS and aluminum, inorganic materials such as glass, and organic materials such as polyimide, transparent polyimide (CPI), polyethylene terephthalate (PET), and polyethylene (PE).

[0090] The laminate of the present invention is not limited to the laminate shown as an example above, but may also be a structure having a first member and a second member, each having a smooth surface, and an adhesive layer (a cured product of a sheet-like sealing material) that bonds them together.

[0091] 3. Sheet-shaped sealing material and method for manufacturing laminate The above-mentioned sheet-like sealing material and laminate can be produced by any method as long as the object and effect of the present invention are not impaired. For example, they can be produced by the following method, but are not limited to this method. First, a composition containing an epoxy compound, a curing agent, and optional components such as a tackifier, an oxetanyl group-containing compound, a dye, and other components is prepared, and this is dissolved in a solvent at 30°C or below to form a varnish. Note that when a curing agent in which a microcapsule-type curing agent is dispersed in a resin such as an epoxy compound is used, the resin may be used directly as a raw material for the sheet-like sealing material.

[0092] Examples of the solvent include aromatic solvents such as toluene and xylene; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ethers such as ether, dibutyl ether, tetrahydrofuran, dioxane, ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether, propylene glycol or dialkyl ether; aprotic polar solvents such as N-methylpyrrolidone, dimethylimidazolidinone and dimethylformaldehyde; and esters such as ethyl acetate and butyl acetate.

[0093] When preparing the varnish, the components may be mixed at once, or the epoxy compound may be dissolved in a solvent and then the other components may be mixed in. Examples of methods for mixing the components include known stirring methods and triple-roll kneading methods.

[0094] Next, the varnish is applied onto a separator, and the solvent is removed. The method for applying the varnish is not particularly limited, and examples include screen printing, dispenser application, and various roll methods. The thickness of the applied varnish is appropriately selected depending on the desired film thickness of the sheet-like sealing material. The drying temperature and drying time of the varnish are preferably those at which the epoxy compound does not harden. For example, the drying temperature is 20 to 100°C, and the drying time can be, for example, about 1 minute to 3 hours. The drying method is not particularly limited, and examples include hot air drying and vacuum drying. The above-mentioned sheet-like sealing material is thus obtained.

[0095] The laminate described above can be obtained by laminating the obtained sheet-like sealing material with a desired member and curing it as necessary. The temperature at this time is not particularly limited, but for example, heating to 60°C or higher and 80°C or lower makes it easier to adhere the sheet-like sealing material to the desired member. The method for laminating the sheet-like sealing material with the desired member is not particularly limited, and for example, the desired members may be placed on both sides of the sheet-like sealing material and simultaneously thermocompressed. However, it is more preferable to place a substrate on one side of the sheet-like sealing material and thermocompression bond it, and then place another substrate on the other side of the sheet-like sealing material and thermocompression bond them.

[0096] Furthermore, the sheet-shaped sealing material can be cured by heating at 100°C as described above, but it may also be cured at a temperature higher than 100°C or lower than 100°C. Specifically, the heating temperature is preferably 60°C or higher and 200°C or lower, and more preferably 70°C or higher and 120°C or lower. Furthermore, the heating time can be appropriately selected according to the heating temperature, and is preferably 20 minutes or higher and 60 minutes or lower. By using the heating temperature and heating time, the epoxy compound in the sheet-shaped sealing material can be sufficiently cured. [Example]

[0097] The present invention will be described below with reference to examples, which should not be construed as limiting the scope of the present invention.

[0098] [material] In the examples and comparative examples, the following materials were used.

[0099] [Epoxy Compound] CEL2021P: a compound represented by the following formula (Celloxide 2021P, manufactured by Daicel Corporation, viscosity at 25°C measured with a Brookfield viscometer: 220 to 270 mPa s) [ka] YL980: Bisphenol A epoxy resin (YL980, manufactured by Mitsubishi Chemical Corporation, weight average molecular weight (Mw) 180-190) YL983U: Bisphenol F epoxy resin (YL983U, manufactured by Mitsubishi Chemical Corporation, weight average molecular weight (Mw) 165-175) JER4005P: Bisphenol F epoxy resin (JER4005P, manufactured by Mitsubishi Chemical Corporation), weight-average molecular weight (Mw) 2000 EP-4040L: A mixture of monofunctional and difunctional epoxy resins with flexible molecular chains (EP-4040L, manufactured by ADEKA Corporation), with a weight-average molecular weight (Mw) of 1000 YX6954-B35: Biphenyl-type epoxy resin (YX6954-B35, manufactured by Mitsubishi Chemical Corporation), weight-average molecular weight (Mw) 36,691

[0100] [Oxetanyl group-containing compound] OXT-221: 3,3'-(oxybismethylene)bis(3-ethyloxetane) (OXT-221, manufactured by Toagosei Co., Ltd.)

[0101] [Curing agent] HX-3742: Microencapsulated imidazole curing agent (dispersion medium: epoxy resin, curing component amount: 30 to 40 mass%, Novacure (registered trademark) HX-3742, manufactured by Asahi Kasei Corporation) HX-3722: Microencapsulated imidazole curing agent (dispersion medium: epoxy resin, hardener content: 30-40% by mass, Novacure (registered trademark) HX-3722, manufactured by Asahi Kasei Corporation) HXA-3922HP: Microencapsulated imidazole curing agent (dispersion medium: epoxy resin, curing component amount: 30-40% by mass, Novacure (registered trademark) HX-3922, manufactured by Asahi Kasei Corporation) HXA-4922HP: Microencapsulated imidazole curing agent (dispersion medium: epoxy resin, curing component amount: 30-40% by mass, Novacure (registered trademark) HXA-4922HP, manufactured by Asahi Kasei Corporation) HXA-9322HP: Microencapsulated imidazole curing agent (dispersion medium: epoxy resin, curing component amount: 30 to 40 mass % Novacure (registered trademark) HXA-9322HP, manufactured by Asahi Kasei Corporation) TA-100: Sulfonium salt-based thermal acid generator (TA-100, manufactured by San-Apro Co., Ltd.) TA-100FG: Sulfonium salt-based thermal acid generator (TA-100FG, manufactured by San-Apro Co., Ltd.) CXC-1733: Thermal cationic polymerization initiator (K-Pure CXC-1733, King Industries)

[0102] [Tackifier] K-125: Terpene phenol resin (YS Polyster K-125), softening point 125°C ± 5°C G-125: Terpene phenol resin (YS Polyster G-125), softening point 125°C ± 5°C

[0103] [Leveling Agent] BYK302: Polyether-modified polydimethylsiloxane (BYK302, manufactured by BYK-Chemie)

[0104] 〔dye〕 Oil Black 860: CI Solvent Black 3 (Orient Chemical Co., Ltd.)

[0105] 1. Preparation of sheet-shaped sealing material [Example 1] An epoxy compound, a curing agent, a tackifier, a leveling agent, and a solvent, methyl ethyl ketone (MEK), were added to a flask in the mass ratios shown in Table 1, and the mixture was stirred and dissolved at room temperature to obtain a varnish of a thermosetting resin composition.

[0106] The varnish was applied to a separator (PET75-H270, 75 μm thick, manufactured by Nichiei Shinka Co., Ltd.) with an applicator so that the film thickness after drying would be approximately 20 μm. This was dried in an inert oven at 80°C for 3 minutes to dry and remove the MEK, yielding a sheet-like sealing material.

[0107] [Examples 2 to 8 and Comparative Example 1] A sheet-shaped sealing material was obtained in the same manner as in Example 1, except that the composition of the thermosetting resin composition was changed to the composition shown in Table 1.

[0108] Comparative Example 2 A sheet-shaped sealing material was obtained in the same manner as in Example 1, except that a commercially available SANCUARY DH425 (manufactured by San-A Kaken Co., Ltd., acrylic adhesive) was used.

[0109] 2. Evaluation The sheet-like sealing materials produced in the examples and comparative examples were evaluated by the following methods. The results are shown in Table 1.

[0110] (1) Comparison of peel strength when heated at 100°C for 60 minutes and when heated at 100°C for 30 minutes (thermal hardening at 100°C) In the separator / sealing sheet laminates prepared in the Examples and Comparative Examples, alkali-free glass (manufactured by Matsunami Glass Co., Ltd., 50 mm x 70 mm, 0.2 mm thick) was adhered to one side of the sealing sheet (the side opposite the separator) and thermocompression-bonded at 70°C. The separator was then peeled off, and an aluminum-vapor-deposited PET film (Alpet 9-100 manufactured by Panac Corporation) was adhered to the sealing sheet on the side opposite the alkali-free glass and thermocompression-bonded at 70°C to obtain a test specimen. The sealing sheet and aluminum-vapor-deposited PET film were 25 mm wide and 100 mm long. The laminate was then heated at 100°C for 30 minutes to cure the alicyclic epoxy compound (A-1) and aromatic ring-containing epoxy compound (A-2) in the sealing sheet. Thereafter, the alkali-free glass was fixed vertically to the jig of a universal testing machine (2200X manufactured by Intesco), and the aluminum-deposited PET film was peeled off vertically at a peeling rate of 30 mm / min to measure the peel strength. Furthermore, a laminate consisting of alkali-free glass / sealing sheet / aluminum-deposited PET film was prepared in the same manner as above and heated at 100°C for 60 minutes. The peel strength was then measured in the same manner as above. These results were evaluated according to the following criteria. ○: The peel strength of the sheet sealant against alkali-free glass when heated at 100°C for 60 minutes is within ±10% (0.9 to 1.1 times) of the peel strength of the sheet sealant against alkali-free glass when heated at 100°C for 30 minutes. ×: The peel strength of the sheet sealant against alkali-free glass when heated at 100°C for 60 minutes is not within ±10% (0.9 to 1.1 times) of the peel strength of the sheet sealant against alkali-free glass when heated at 100°C for 30 minutes.

[0111] (2) Stability at 25°C The stability at 25°C was evaluated by the calorific value measured by a differential scanning calorimeter (DSC). Specifically, 10 mg of the sheet-shaped sealing material immediately after production was sampled and placed in an aluminum cell for DSC measurement to prepare a measurement test sample. Then, the calorific value was determined when the temperature characteristics of the measurement test sample were measured at a temperature rise rate of 5°C / min and a measurement temperature range of 20°C to 300°C. In addition, the calorific value was similarly measured for a sheet-shaped sealing material that had been stored at 25°C for one day after production. These results were then compared and evaluated according to the following criteria. The evaluation was based on the following criteria. ○: The heat generation rate measured by DSC of the sheet sealant after storage for one day at 25°C is within ±5% (0.95 to 1.05 times) of the heat generation rate measured by DSC of the sheet sealant before storage. ×: The calorific value measured by DSC of the sheet sealant after storage for 1 day at 25°C does not fall within the range of ±5% (0.95 to 1.05 times) of the calorific value measured by DSC of the sheet sealant before storage.

[0112] (3) Storage modulus E' of sheet sealing material at 35°C The sheet-like sealing materials produced in the examples and comparative examples were cured as a single unit at 100°C (30 minutes for examples 1 to 8). Dynamic viscoelasticity measurements were then performed from 20°C to 150°C at a temperature increase rate of 5°C / min and a frequency of 1 Hz. The storage modulus (E') at 35°C was determined.

[0113] (4) Peel strength In the separator / sealing sheet laminates prepared in the Examples and Comparative Examples, alkali-free glass (manufactured by Matsunami Glass Co., Ltd., 50 mm x 70 mm, 0.2 mm thick) was adhered to one side of the sealing sheet (the side opposite the separator) and thermocompression-bonded at 70°C. The separator was then peeled off, and an aluminum-vapor-deposited PET film (Alpet 9-100 manufactured by Panac Corporation) was adhered to the sealing sheet on the side opposite the alkali-free glass and thermocompression-bonded at 70°C to obtain a test specimen. The sealing sheet and aluminum-vapor-deposited PET film were 25 mm wide and 100 mm long. The laminate was then heated at 100°C for 30 minutes to cure the alicyclic epoxy compound (A-1) and aromatic ring-containing epoxy compound (A-2) in the sealing sheet. Thereafter, the alkali-free glass was fixed vertically to the jig of a universal testing machine (Intesco 2200X), and the aluminum-deposited PET film was peeled off vertically at a peeling rate of 30 mm / min to measure the adhesive strength. [Table 1]

[0114] The commercially available acrylic adhesive could not be cured by heating and had low stability at 25°C. In other words, the desired performance was not obtained (Comparative Example 2). Furthermore, the sheet-like sealing material of Comparative Example 1 showed a large difference in peel strength between after heating at 100°C for 30 minutes and after heating at 100°C for 60 minutes, which made it clear that it could not be cured by heating at 100°C for a short period of time. Furthermore, the sheet-like sealing material had a low peel strength due to factors such as an excessively high storage modulus E' after curing.

[0115] On the other hand, when a film containing an epoxy compound and a curing agent was laminated with alkali-free glass and heated at 100°C for 60 minutes, and the peel strength from the alkali-free glass was 0.9 to 1.1 times the peel strength from the alkali-free glass after laminating with alkali-free glass and heating at 100°C for 30 minutes, and the storage modulus E' of the cured product at 35°C was 0.1 GPa to 2.0 GPa, the peel strength of the cured product was sufficiently high (Examples 1 to 8). [Industrial Applicability]

[0116] The sheet-like sealing material of the present invention can be cured at a low temperature in a short time, yet has excellent adhesiveness to various members, and is therefore very useful as a member for bonding various members of various display devices.

Claims

1. An epoxy compound and a curing agent are included, A sheet-like sealing material that is uncured at temperatures below 25°C, the sheet-like sealing material has a peel strength from the alkali-free glass after being laminated with the alkali-free glass and heated at 100°C for 60 minutes that is 0.9 to 1.1 times the peel strength from the alkali-free glass after being laminated with the alkali-free glass and heated at 100°C for 30 minutes; the storage modulus E' at 35°C, as measured by dynamic viscoelasticity measurement of the cured product at a heating rate of 5°C / min and a frequency of 1 Hz, is 0.1 GPa or more and 2.5 GPa or less; Sheet-type sealing material.

2. the curing agent is a microcapsule-type curing agent in which at least one curing component selected from the group consisting of an imidazole-based compound, an amine-based compound, and an amine adduct is encapsulated in microcapsules, and / or an acid generator having a sulfonium salt structure; The sheet-like sealing material according to claim 1 .

3. Further comprising a dye, The sheet-like sealing material according to claim 1 .

4. a first member, a second member, and an adhesive layer that bonds the first member and the second member; At least one of the first member and the second member has irregularities with a height of 1 μm or more and 100 μm or less on a surface adjacent to the adhesive layer, The adhesive layer is a cured product of the sheet-like sealing material according to any one of claims 1 to 3. Laminate.

5. The height of the irregularities is 80% or less of the thickness of the adhesive layer. The laminate according to claim 4.

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